On May 31, 1994, a Bell 47G3 SOLOY (registration N121CD) was involved in an aviation accident near Friendsville, MD. Investigators recorded the probable cause as: THE PARTIAL FAILURE OF THE TURBINE ENGINE FOR UNDETERMINED REASONS, DURING AN AGRICULTURE MANEUVER AT LOW ALTITUDE, OVER TERRAIN UNSUITABLE FOR AN AUTOROTATION. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aerial application helicopter experienced a partial engine power loss while over hilly terrain. The pilot attempted to reach a clearing but struck a tree, causing the aircraft to land hard. Post-accident engine tests revealed only impact-related damage.
Accident Overview
Approximately 30 minutes into an aerial application flight, a turbine-engine-converted Bell 47 helicopter experienced a partial loss of engine power. At the time, the aircraft was flying over hilly terrain interspersed with tree lines. The pilot was conducting an uphill run at an altitude of 30 to 40 feet above the trees and a speed of 60 to 65 miles per hour. Upon sensing the power loss, the pilot attempted to fly toward an open area while maintaining partial power. As the helicopter approached the edge of a clearing, it struck a tree. After the helicopter came to rest on the ground, the pilot shut down the engine using the twist grip throttle.
Post-Accident Examination
Investigators examined the transmission, freewheeling unit, and tail rotor gearbox; no defects were noted in these components. Examination of the engine revealed accident-related impact damage to the combustion liner. The damaged liner was replaced, and the engine subsequently performed normally during a test run.